SHR-od is a novel strain of rat that spontaneously develops hypertension and has a defect of ascorbic acid (AsA) biosynthesis. The osteogenic disorder Shionogi (ODS) rat is normotensive and also unable to synthesize AsA. To investigate whether or not genetic hypertension affects AsA metabolism, we compared the AsA metabolisms of SHR-od and ODS rats. In this study, a physiological dose of AsA equivalent to the AsA requirement in ODS rats was administered to rats intraperitoneally (i.p. group) or orally (oral group). We measured AsA concentrations in the serum, liver, kidney, adrenal glands, and spleen, and the amount of AsA excreted into the urine. At 25 wk of age (hypertensive status), the AsA concentrations of all tissues tested were significantly lower in SHR-od than in ODS rats in both the i.p. and oral groups. In the i.p. group, the amount of urinary AsA in SHR-od was also lower than that in ODS rats. At 4 wk of age (before the onset of hypertension), liver and spleen AsA concentrations in SHR-od were lower than those in ODS rats in both the i.p. and oral groups. Urinary AsA excretion from SHR-od was not different between the two groups. Our data suggest that the requirement for AsA in SHR-od is increased to maintain tissue AsA concentrations equivalent to those in ODS rats, and that a larger part of the AsA administered to rats in this study is degraded in SHR-od as compared to ODS rats.

View full abstract

We investigated the interrelationships between behavior and serum amino acid concentrations in iron-deficient anemic rats. Concentrations of proline, alanine, glycine, and phenylalanine in serum samples were significantly higher than those in rats fed a normal diet, while serum threonine, glutamic acid, and valine levels were significantly lower. Activities of locomotion, rearing, hole-poking, and grooming, determined by using a hole board apparatus, were significantly reduced in anemic rats. The supplementation of inorganic iron and amino acids proline, arginine, or glutamic acid to the normal diet lead to the recovery of normal behavior. Proline enhanced a significant increase in the number of red blood cells and hemoglobin by the supplementation of iron alone. We propose that the combination of amino acid (especially proline) and inorganic iron might lead to an improvement in behavioral disorders caused by iron-deficient anemia.

View full abstract

The dietary habits and nutritional status of Vietnamese primary school girls were investigated using a cross-sectional survey. We interviewed 348 girls aged 7 to 9 yr old, randomly selected from three rural (n=193) and two urban (n=155) primary schools. The nutritional status of the children was evaluated by anthropometric and biochemical data. Dietary data were calculated based on the results of a 24-h recall interview carried out for three consecutive days. The dietary macronutrient pattern of the rural group showed a deficiency of energy, fat, animal protein, and fiber content. On the other hand, high animal protein ratio, deficiency of fiber consumption, low polyunsaturated fatty acid, and high saturated fatty acid proportions were typically found in the urban group. A high number of rural children skipped lunches, resulting in low energy consumption; however, frequently skipped breakfast in the urban group did not influence total energy consumption because of extra meals taken. The mean height of rural children was 5.8 cm less than that of their urban counterparts. In addition, 11.4% of wasted rural children needed emergency intervention with energy supplementation. Moreover, a high proportion of children with a high atherogenic index (AI) (41.5%) and low HDL cholesterol (40.9%) were found in the rural group. In contrast, a tendency toward obesity, high cholesterol, LDL cholesterol, and high AI was observed in a proportion of the urban children (5.2%, 15.5%, 12.3%, and 29.0%, respectively).

View full abstract

The effects of taurine on serum cholesterol levels and hepatic cholesterol 7α-hydroxylase activity (CYP 7A1) were studied in rats fed cholestyramine or high amounts of sodium cholate in order to alter the intestinal pool of bile acids. Rats were fed a diet supplemented with 1% cholesterol and 0.25% sodium cholate (high cholesterol, control; C), and C supplemented with 4% cholestyramine (CH) or 0.75% sodium cholate (BA) for 14 d. Taurine groups were fed the diet supplemented with 3% taurine (CT, CHT and BAT). Compared to rats fed C and BA diets, serum cholesterol levels were significantly reduced in rats fed CT and BAT diets, but a significant reduction of serum cholesterol by taurine feeding was not observed in the CHT group as compared to the CH group. An increase in hepatic CYP7A1 activity due to taurine intake was observed in the CT and BAT groups. However, the simultaneous administration of cholestyramine and taurine (CHT group) did not in-crease hepatic CYP7A1 activity compared the intake of cholestyramine only (CH group). A significant increase in fecal bile acid excretion due to taurine intake was found only in rats fed the CT diet. In conclusion, it is suggested that taurine facilitates hepatic CYP7A1 activ-ity regardless of the enlarged intestinal pool of bile acids due to increased intake of exogenous bile acid, and then reduces the serum cholesterol concentration.

View full abstract

Membrane-type serine protease 1 (MT SP1), identical to matriptase, is a recently identified type II transmembrane serine protease. MT-SP 1/matriptase is of consider-able interest for the development, homeostasis, and cancer invasion and metastasis of epithelial tissues. The administration of inhibitors for MT SP 1/matriptase may be effective to suppress the development of tumors where the enzyme may be involved. In the present study, we produced a secreted form of recombinant MT SP 1/matriptase (ekMT-SP1s) that can be activated by enterokinase in vitro and investigated the inhibitory ability of various protease inhibitors toward the recombinant enzyme. The enterokinase-treated ekMT-SP1s (active ekMT-SP1s) cleaved various peptidyl-4-methylcoumaryl-7-amide (MCA) substrates with arginine (or lysine) residue at position P1, and the best substrate was t-butyloxycar-bonyl (Boc)-Gln-Ala-Arg-MCA. The specificity for the synthetic and natural substrates of the active ekMT-SP1s was in good agreement with that of the natural enzyme. Endogenous protease inhibitors tested, except for antithrombin III, showed no or little inhibition on the cleavage of Boc-Gln-Ala-Arg-MCA by the active ekMT-SP1s. Aprotinin showed strong in-hibitory activity toward the cleavage. Food-derived inhibitors, such as soybean trypsin in-hibitor, Bowman-Birk inhibitor, and lima bean trypsin inhibitor inhibited it, while chicken ovomucoid did not. Synthetic inhibitors tested inhibited it, and among them, the inhibitory effect of FOY 305 was strongest. The present findings provide important information for the suppression of cancer invasion and metastasis for which MT-SP1/matriptase is responsible.

View full abstract

Weanling rats were fed respective diets diverse in protein source and content for a full week, and hepatic serine dehydratase (SDH) was examined for its gene expression and activity induction attendant on high protein intake. The protein sources used were three kinds of milk casein, codfish meat, and wheat gluten. The body weight gain (% aug-mentation/wk) increased with increasing protein intake and reached a plateau in both milk casein- and codfish meat-fed rats by protein intake above 2.5g/100g BW/d; however, the body weight gain continued to increase albeit at a slower rate in wheat gluten-fed rats. Quite similar tendencies were also seen in nitrogen balance. The ascent of SDH activity induction and its causal gene expression were characterized as codfish meat>milk casein>>wheat gluten in order of response to protein intake near or more than 4g/100g BW/d. The difference in SDH gene expression among these dietary proteins was substantiated by a confirmation experiment in which six rats of each group were fed 25% or 50% protein diets under the same conditions as above. Hence, the quantity as well as quality of dietary protein turned out to have an influence on SDH gene expression.

View full abstract

Hyroid hormone stimulates hepatic lipogenesis in the rat by increasing the expression of relevant genes, including acetyl-CoA carboxylase and fatty acid synthase. S14 mRNA, which encodes a protein thought to be involved in lipogenesis, responds in parallel. The effects of thyroid hormone on lipogenesis in white and brown adipose tissue are less clear, and may be complicated by indirect effects of the hormone. Rat white and brown preadipocytes were therefore isolated, grown to confluence, and used to test direct effects of thyroid hormone, insulin, and glucose. Lipogenesis was assessed by tritiated water incorporation, and acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS), and S14 mRNAs were measured by Northern analysis. Insulin (1nM) increased lipogenesis about 9-fold in both white and brown adipocytes. Similar increases were seen in the levels of the three mRNAs. Thyroid hormone (1μM) stimulated lipogenesis and acetyl-CoA carboxylase, fatty acid synthase, and S14 mRNA levels up to 2-fold in both types of adipocyte in the presence or absence of insulin. A high carbohydrate level (25mM glucose) had no effect on lipogenesis compared to a low carbohydrate level (5mM glucose) in white and brown adipocytes. There was no synergistic effect on lipogenesis by the combination of thyroid hormone and high carbohydrate level in both types of adipocytes. These experiments have shown that T₃ has small, direct stimulatory effects on lipogenesis in adipocytes. These effects are seen at a pretranslational level, through the coordinate induction of ACC, FAS, and S14 mRNAs. Although lipogenic rates were usually higher in brown adipocytes than white adipocytes, very similar patterns of regulation were seen in the two cell types. These data support the idea that the divergent results seen concerning T₃ regulation of the lipogenic pathway in both brown and white adipose tissue in vivo arise from secondary effects of the alteration of thyroid status.

View full abstract

The effects of dietary 1, 3-diacylglycerol-rich oil (DG oil) on biochemical findings related to glucose and lipid metabolisms were investigated in comparison with triacyl-glycerol oil (TG oil) in normal rats. Young (7 wk-old) and old (8 mo-old) rats were fed a synthetic diet containing 10% (by weight) DG or TG oil for 1, 4, 8, or 12 wk. The body weights, epididymal and perirenal adipose tissue weights, and feed efficiency were not significantly different in the dietary oil groups during any feeding period. The plasma and liver triacyl-glycerol concentrations were not different in the dietary groups, except that the plasma tria-cylglycerol concentrations were rather lower only in the portal vein of rats fed DG oil. The plasma glucose and free fatty acid concentrations were significantly higher in rats fed DG oil as compared to TG oil. In the old rats fed DG oil for 8 wk, the fasted plasma glucose and insulin concentrations were elevated and glucose intolerance was observed. The insulin receptor expression was not different due to dietary oil, but was markedly reduced with aging. Thus, the anti-obesity and lipid-lowering effects of dietary DG oil were not found. Moreover, it appeared that the glucose intolerance might be induced by dietary DG oil, particularly in the old rats.

View full abstract

Anti-obesity effects of a mixture of thiamin, arginine, caffeine, and citric acid (TACO) were investigated in non-insulin dependent diabetic KK mice. Feeding of either arginine or caffeine significantly suppressed an increase in hepatic lipid contents in fasted-refed KK mice. In addition, each component admixed with a low-calorie diet effectively reduced adipose tissue weight in KK mice previously fed a high-calorie diet. The decrease in adipose tissue weight was greater with a mixture of arginine and caffeine, and much greater with TACC than with arginine or caffeine alone. Moreover, plasma insulin concentration was significantly lower in mice fed TACC than in control mice. The anti-obesity effects of TACC were also shown when it was supplemented with a tea beverage. Adipose tissue weight, hepatic triglyceride contents, and plasma insulin concentration were significantly lower in mice given TACC-supplemented tea than in control mice. These results suggest that TACC is effective in reducing adipose tissue mass as well as improving disorders in lipid metabolism

View full abstract

Fifteen commercial samples of citrus fruits grown in Japan were analyzed for their sugar contents by high-performance anion-exchange chromatography (HPAEC) and electrochemical detection (ED) coupled with a stationary phase D₁₀ column prepared using chloromethylated styrene-divinylbenzene copolymer and N, N, N', N'-tetramethyldiaminodecane. Myo-Inositol, glucose, fructose, and sucrose in all of these various citrus fruits could be successfully separated within 25 min using 0.5M NaOH eluent at a flow-rate of 0.4mL/min. Myo-Inositol, as a better nutritional source, was found in all the citrus fruits grown in Japan (0.7±0.04-2.1±0.2g/L). The sugar contents of twelve citrus fruits grown in other countries were also determined.

View full abstract

We investigated the vitamin A status and β-carotene 15, 15'-dioxygenase activity in hairless mice with UV exposure to assess the regulation of vitamin A metabolism after UV irradiation. HR-1 hairless mice were irradiated with UV at 3 J/cm² for 5 d. After UV irradiation, the mice were sacrificed and samples were obtained to analyze the retinoid concentration, expression of RXR-a, and β-carotene 15, 15'-dioxygenase activity. After UV exposure, the skin retinoid concentration was significantly lower as well as the expression of RXR-α. Higher skin β-carotene dioxygenase activity was observed in the UV group as compared to the control group. We found no significant differences in the α-tocopherol concentration or acrolein levels in the skins of the two groups. In conclusion, the elevation of β-carotene 15, 15'-dioxygenase activity in hairless mice after UV exposure may be a response to reduction of the skin retinoid concentration.

View full abstract

In Escherichia coil, 4-(phosphohydroxy)-L-threonine and 1-deoxy-D-xylulose 5-phosphate are believed to be direct precursors of vitamin B₆ (B₆), and 1-deoxy-D-xylulose 5-phosphate synthase (Dxs) and transketolase could catalyze the formation of each precur-sor. In this report, the possible involvement Dxs and transketolase (Tkt) in B6 biosynthesis in Bacillus subtilis was investigated. The gene disruptant of tkt and conditional mutants of dxs were constructed, and their ability of B6 biosynthesis was examined. It was found that the tkt disruptants retain the ability to synthesize B₆. The conditional mutant of dxs synthesized the same amount of B₆ per dry cell weight as the wild-type strain. Therefore, it is very likely that neither Dxs nor transketolase is involved in B₆ biosynthesis in B, subtilis.

View full abstract

The effects of sago starch content in diets on the status of lipid peroxidation and antioxidative enzyme activities were examined with rats fed cholesterol-free and choles-terol-enriched diets. Despite the diets with and without supplemental cholesterol, both food intake and the value of plasma thiobarbituric acid reactive substances (TBARS) showed a lower tendency or lower values in the rats fed the diet with a high ratio of sago starch as compared to a low ratio. Liver superoxide dismutase (SOD) and catalase activities, and serum and liver α-tocopherol concentrations were higher in the rats fed the cholesterol-free and enriched diets with a high ratio of sago starch as compared to a low ratio. From these results, it was suggested that a higher ratio of sago starch in the diet may be useful to keep the in vivo oxidative status at a lower level.

View full abstract